The present invention relates to remote switch controllers, and more particularly to an improved battery powered programmable remote switch controller having extended battery life that is adaptable for use in controlling irrigation valves.
Programmable irrigation valve controllers are well known in the art. Such controllers are used to open and close irrigation valves by providing electric current to solenoids located in close proximity to the valves. Relatively large electric currents are required to activate and deactivate such solenoids. Providing this required electricity is a simple matter if an external power source is readily available, such as a power line. However, many controllers must be located at remote field locations where it is impossible or impractical to run a power line or otherwise provide an external power source. Accordingly, programmable battery powered irrigation controllers have been developed.
The most significant limitation of existing battery powered irrigation controllers is battery life. Two voltage levels are generally required by such controllers: a low voltage level (which can be supplied by batteries, e.g. 3.5 volts) to operate the programming circuitry, and a higher voltage level (which can be supplied by a second set of batteries, e.g. 9 volts) to provide the necessary electrical impulses to operate the valve solenoids. The batteries on most existing battery powered controllers must be changed every few months, making them inconvenient to maintain and potentially unreliable to depend on for controlling irrigation cycles. At least one controller has addressed the problem of conserving the low voltage batteries used to operate the computing circuitry. In U.S. Pat. No. 4,423,484 to Hamilton, the microcomputer is turned off between cycles thereby conserving the low voltage batteries. However, the Hamilton controller does not address conservation of the higher voltage batteries used to operate the solenoids.
It is typical for a battery powered irrigation controller to use charging capacitors to operate the valve latching solenoids. These are generally large capacitors of 1000 micro farads or more. Most controllers (including Hamilton) maintain these capacitors in a charged condition, ready for immediate discharge to the solenoid upon receipt of a signal from the microprocessor (see e.g. U.S. Pat. No. 4,718,454 to Appleby). In addition, in most controllers these capacitors have an uninterrupted connection back to the high voltage (e.g. 9, 12 or 18 volts) batteries from which they are charged. Both of these situations reduce the life of the high voltage batteries, and give rise to other potential problems with the controller.
It is known that all charged capacitors leak over time. This places a constant drain on the high voltage batteries to which they are connected. Such leakage significantly increases with temperature increases. Thus, a fully charged capacitor in a controller located in the middle of an unshaded field during the hot summer months can rapidly deplete the high voltage batteries, even when not in use. The larger the capacitor, the larger the leakage current. Also the higher the ambient temperature, the higher the leakage. This leakage is very significant and could be as much as hundreds of microamps. The leakage causes the capacitor to draw on the battery power supply in order to stay fully charged, thereby wasting energy and leading to the frequent need to change batteries without even any solenoid operation. Preventing this leakage would conserve the life of the high voltage batteries.
Battery operated controllers such as Hamilton use the high voltage batteries for operating both the solenoids and the electronics. Since most low power circuits operate from 3 to 5 volts DC, the high voltage batteries must be reduced and regulated, thereby wasting a considerable amount of energy. Alternatively, a low voltage battery may use a boost converter (voltage multiplier) to step up the voltage as in U.S. Pat. No. 5,572,108 to Windes.
In all controllers, the large capacitors are fully discharged in order to operate the valve solenoids. The capacitors are then recharged from the high voltage batteries. At the instant the discharge occurs, current may also be drawn directly from the high voltage batteries themselves, resulting in unnecessary depletion of the high voltage batteries.
Changing the programming for remotely placed valve controllers also poses an ever present problem. With the change of seasons come changes in the amount irrigation water needed. The additional water required during hot summer months translates to longer open times for irrigation valves. Conversely, the reduced demand for water during the winter season translates to shorter or no open times for such valves. Changes in weather and weather patterns may also affect irrigation valve run times. Also different crops have different water requirements.
In order to address the ever present need to change irrigation valve run times, some remote irrigation valve controllers include a radio receiver which remains operational at all times. In this way, a signal can be transmitted to the receiver at any time and used to change the programming (run times) of the irrigation valves. However, maintaining a radio receiver in the xe2x80x9conxe2x80x9d position over long periods of time requires considerable power, and will rapidly deplete the batteries of a remotely located controller. Frequently changing the batteries requires gaining access to the controller in the field which can be messy (especially in a cold, dark and/or damp environment), and may introduce unwanted foreign or corrosive materials to the delicate circuitry inside. In addition, the receiver may pick up an errant signal resulting in improper programming. Finally, unless the controller also includes a transmitter (another drain on the batteries), there is no way to confirm the receipt of programming instructions sent via radio.
The programming of other controllers may be changed by directly accessing the controller in the field. This is typically accomplished by opening the receptacle in which the controller is located and plugging a line into the controller to download new programming. As with a battery change, accessing the controller in this way may also introduce dust, dirt, debris or other undesirable material to the delicate internal circuitry of the controller. It is therefore desirable to avoid direct physical access to the remotely located controller in the field.
The need for battery powered programmable remote control switching systems is not limited to irrigation valves. Numerous industrial, utility and commercial applications also involve remote switches which must be reliably turned on and off at scheduled times in order to initiate or terminate processes, open or close gates, etc.
The present invention overcomes the disadvantages of prior art remote switching systems by providing a battery powered controller that conserves the life of the battery(ies) which operates the internal controller circuitry as well as the external switches (e.g. latching valve solenoids), and which may be easily programmed without direct physical access to the controller that might otherwise expose the internal circuitry to unwanted foreign material.
In the preferred embodiment, two sets of batteries are used in the present invention. A first set of one or more low voltage batteries (typically 3.0 to 3.6 volts) is dedicated to the internal circuitry (e.g. microprocessor). This low voltage powers the microprocessor directly without the need for regulation which would otherwise waste energy.
A second set of one or more high voltage batteries is provided which is only used for charging the capacitors which discharge into the remote switches (e.g. to operate the solenoids). This obviates any need to reduce or regulate this battery source for use by the electronic circuitry, so this potential energy loss is avoided.
In the present invention, the large capacitors are not charged until just a few seconds before the solenoid is to be energized. At that point, the microprocessor enables a transistor to turn on and charge such a capacitor. After a measured time interval, depending on the capacity of the capacitor (e.g. about 5 RC time constants), for all intents and purposes, the capacitor becomes fully charged. Following an isolation step (discussed below), a switching device (e.g. relay, triac, transistor, or the like) is used to quickly discharge the capacitor into the switch (e.g. a latching solenoid or latching relay). Thereafter, the capacitor remains discharged waiting for the next operation. Leaving the capacitor uncharged for long periods of time effectively eliminates capacitive leakage current.
The present invention avoids another source of energy waste found in typical battery operation. With existing controllers, when the capacitor discharges, the charging resistor is still connected from the high voltage battery source to the remote switch. This results in a further draw of current from the battery directly by the switch, which also depletes the battery. In the present design, the charging circuit is disabled and isolated by the charging transistor just prior to the capacitive discharge, thereby eliminating this unnecessary power drain. The circuit remains isolated for another measured interval (e.g. approximately 5 RC time constants, a few seconds) before the next operation, at which point the high voltage battery source is again connected to the capacitor for charging followed again by isolation immediately before discharge.
Lithium batteries are recommended as the power source for both the low and high voltage circuits. Lithium batteries have extremely long shelf life (10 years), extremely low self discharge (less than 1% per year), and are rated for full performance over a wide temperature range up to 85 degrees Centigrade. Most other types of batteries would self discharge under typical ambient conditions within a year. Also, lithium batteries have double the energy capacity of alkaline batteries, and are lighter in weight.
The microprocessor is capable of maintaining a set of programming instructions for one or more switches (e.g. valve solenoids) under its control, including at least one default program. The present invention provides a novel approach to changing the programming or initiating a default program which allows the controller to remain insulated from the exterior environment in order to preserve the controller circuitry and maximize the life of the batteries of the controller.
There are many possible remote locations for controllers of the present invention. In order to avoid damage from climatic elements or from vandalism, such controllers are typically located inside closable receptacles that may be locked for added protection. Such a receptacle may be attached to a wall, placed behind a door, located under a surface, or otherwise conveniently mounted in the vicinity of the switches to be controlled.
In one aspect of the invention for use in irrigation systems, the controller of the present invention may be placed in a closable box that is buried in the ground with its upper surface flush with the surface of the ground around it. The upper surface of such a box is usually a hinged or removable lid which allows access to the interior. The lid may be locked to the box in order to prevent unauthorized access.
A small radio receiver is included in the internal circuitry of the controller of the present invention. However, instead of remaining in a constantly operational condition, the power supply to this receiver is controlled by a magnetic switch which must be activated in order for the receiver to turn xe2x80x9con.xe2x80x9d Unless the magnetic switch is closed, the receiver is dormant and does not draw any power. The magnetic switch is located at an edge of the controller circuitry, and the circuitry mounted preferably near a wall, lid or door of the locked receptacle in which the controller is located. Where the controller cannot be mounted directly to a wall, lid or door of the receptacle, one aspect of the invention includes a conductive metallic member that may be provided between the magnetic switch and the edge of the receptacle to provide conductivity over this short gap. This member may take a variety of forms so long as it is made of a suitable conductive metal such as a rod, screw, nail, strip, laminate or other ferrous material. One end of the member is attached in the vicinity of the magnetic switch, and the other end is attached to a nearby wall, lid or door of the locked receptacle. A screw may be used for this purpose by drilling flush it into the wall, lid or door in the very near proximity of the magnetic switch. Such a screw must be made of conductive material, and be of sufficient length to extend from the wall, lid or door to very close proximity with the magnetic switch in order to have a conductive relationship with the switch. In this way, a magnet that is brought near the magnetic switch or the conductive member will cause the magnetic switch to close, thereby activating the radio receiver without opening the receptacle.
In one aspect of the invention, a transmitter may also be provided in the controller circuitry. Power to the transmitter is also controlled by the magnetic switch such that the transmitter is inactive unless the magnetic switch is closed. The transmitter is used to confirm the current programming of the controller, or to confirm receipt of new programming.
In one aspect of the invention, all of the circuitry of the present invention including the batteries, transmitter/receiver, and the magnetic switch are potted (encapsulated) so as to prevent impurities from corroding any of the component parts. This makes the batteries inaccessible. However, because the of the power conserving features of the present invention, the batteries have a very, very long life (on the order of 10 years) such that at the end of that time, the controller unit is simply removed and replaced.
A separate hand held programming unit is also provided for transmitting a program to the controller. This hand held unit includes a data input mechanism (e.g. push buttons, clock, switches, etc.), a display (LCD, LED, lights, or the like) and circuitry to receive, maintain and download the inputted data. The hand held unit is designed to hold numerous different sets of input (i.e., programs containing on/off switching instructions to be downloaded to the controller). The hand held unit also includes transmitter and receiver circuitry, and its own power supply. Importantly, the hand held unit also includes a magnet that is strong enough to trip the magnetic switch on the controller from the outside of the controller receptacle either directly or through the conductive member. The magnet is preferably integrated into the hand held unit, but may be provided separately.
In a typical use, the batteries, circuitry and magnetic switch of the controller are encapsulated (potted), and the encapsulated unit is mounted on or near a wall, lid or door of an environmentally protective receptacle which may be locked. If necessary, a conductive member may be attached to the encapsulated unit near the magnetic switch and extended a short distance to the wall, lid or door of the receptacle. The location of the magnet or conductive member should be marked on the outside of the receptacle.
The user inputs a set of programming instructions to the hand held unit. The user then travels to the controller location, and places the magnet of the hand held unit on the outside of the receptacle in the vicinity of the conductive member or magnetic switch of the controller. This activates the magnetic switch turning on the receiver and, if provided, the transmitter of the controller. The user then causes the hand held unit to download the programming instructions through its transmitter. These instructions are received by the controller in a matter of seconds. If a transmitter is provided on the controller, the hand held unit can then interrogate the controller to confirm the new programming. Once confirmed, the hand held unit is removed from the receptacle and the controller receiver/transmitter shuts off. In this way, not only is very little power required to program the controller, it is also unnecessary to make physical contact with the controller thereby avoiding the introduction of harmful foreign or corrosive materials from the environment. These aspects greatly extend the life of the battery operated controller while also allowing easy changes to be made to the controller programming. In addition by requiring magnetic activation external interference is avoided.
In another aspect of the invention, at least one default program is provided in the controller. For illustrative purposes and by way of example only, and without limiting the scope of the appended claims herein, such a program could provide for serial operation of each switch for a pre-determined time interval (e.g., one minute each in order to xe2x80x9cmanuallyxe2x80x9d test each valve), and/or such a program could be a custom set of pre-determined switching operations designed as the default set of instructions for the given installation.
When the magnet of the hand held unit activates the magnetic switch of the controller, after a pre-determined time delay (e.g. 15 seconds, 30 seconds, 45 seconds, 60 seconds, etc.) the default programing initiated. The delay allows the user time to download programming from the hand held unit, interrogate the controller (if applicable), and remove the magnet thereby deactivating the magnetic switch before the default program starts. The default program only operates as long as the magnetic switch is activated. Thus, if the default program is a serial test of each switch or valve control, if a failure is detected (e.g. a leaking pipe) removal of the magnet from the switch will end the default program and close the switch (e.g. cutting off flow to the leaking pipe).
In a very simple aspect of the invention, the controller has only custom programming and a default program. The custom programming operates according to the specific needs of the installation, and cannot be changed. Accordingly, no hand held unit, radio transmitters or radio receivers are required. The default program is activated by using a magnet to close the magnetic switch. Removal of the magnet ends the default program and returns the unit to its custom programming.
It is therefore a primary object of the present invention to provide an improved battery powered programmable remote switch controller having numerous features which extend the life of the controller batteries.
It is also a primary object of the present invention to provide a battery powered programmable remote switch controller which includes a magnetic switch for activation of an on-board receiver, and a hand held unit with magnet and transmitter for downloading programming to the controller.
It is a further object of the present invention to provide a battery powered programmable remote switch controller which includes a magnetic switch and a default program, the default program being activated by operation of the magnetic after a time delay.
It is a further important object of the present invention to extend the life of the batteries in a battery powered programmable remote switch controller by not maintaining its activation capacitors in a fully charged condition at all times.
It is a further important object of the present invention to extend the life of the batteries in a battery powered programmable remote switch controller with circuitry which does not allow each capacitor to be charged until just before it is known to be needed for discharge to activate a switch.
It is a further important object of the present invention to extend the life of the batteries in a battery powered programmable remote switch controller using a load isolation circuit which engages to separate the high voltage batteries from the capacitors immediately prior to discharge of the capacitors.
It is a further important object of the present invention to extend the life of the batteries in a battery powered programmable remote switch controller using a circuit which isolates the capacitor(s) from the high voltage batteries several milliseconds before capacitor discharge, so as not to also draw on the capacitor-charging batteries during the discharge operation.
It is a further object of the present invention to extend the life of the batteries in a battery powered programmable remote switch controller in which the circuitry does not perform continuous power consuming input sampling, but instead either samples only once a second for several milliseconds, or reads the input at the beginning of a programmed operation.
It is a further object of the present invention to extend the life of the batteries in a battery powered radio programmable remote switch controller which includes a receiver by providing a magnetic switch to turn the receiver on and off, such that the receiver is dormant except when the magnetic switch is occasionally activated.
It is a further object of the present invention to minimize spurious, false and/or interfering radio frequency (RF) signals in a battery powered radio programmable remote switch controller by providing a receiver in the controller that is only occasionally activated using a magnetic switch.
It is a further object of the present invention to allow a battery powered radio programmable remote switch controller to be locked inside a receptacle where it is protected from the outside environment and from vandalism by providing a receiver in the controller that may be activated from the exterior of the receptacle using a magnetic switch.
It is a further object of the present invention to allow a battery powered radio programmable remote switch controller to receive programing while locked inside a protective housing by providing a receiver in the controller that may be activated from the exterior of the housing using a magnetic switch, and by providing a hand held unit with magnet and transmitter for, respectively, switching on the receiver and downloading programming.
It is a further object of the present invention to provide speedy radio programming of a battery powered remote switch controller.
It is a further object of the present invention to minimize the possibility of accidental improper programming of adjacent battery powered radio programmable remote switch controllers by providing a separate magnetic switch on each controller for individual activation of the receiver of each controller.
It is a further object of the present invention to provide a battery powered programmable remote switch controller in which the circuitry is encapsulated (potted or otherwise sealed) so as to prevent impurities from corroding any of the component parts, and to minimize exposure to electrostatic discharge.
It is a further object of the present invention to provide a battery powered programmable remote switch controller which uses lithium batteries for both the high and low voltage batteries because of their greater reliability and long life.
It is a further object of the present invention to provide a battery powered programmable remote switch controller which is adaptable for use for controlling irrigation valves.
It is a further object of the present invention to provide a battery powered programmable remote switch controller which is adaptable for use for controlling industrial, commercial, or utility switches or controls.
Other objects of the invention will be apparent from the detailed descriptions and the claims herein.